Suction box extraction apparatus



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March 17, 1959 E. A. POIRIER 2,877,693

SUCTION BOX EXTRACTION APPARATUS Filed Jan. 11, 1957 5 Sheets-Sheet 1VIII/A P' P2 P "iPlh s mf lliisi lisn I Il INVENTOR.

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ATTORNEY March 17, 1959 E. A. POIRIER SUCT'ION BOX EXTRACTION APPARATUSFiled Jan. 111, 1957 5 sheets sheet 2 I /IOc /IOd Ole FIG. 4

FIG. 5

INVENTOR.

ATTORNEY March 17, 1959 I E. A. POIRIER 2,877,693

' SUCTION BOX EXTRACTION APPARATUS Filed Jan. 11, 1957 v 5 Sheets-sheaf,3

FIG. 7

-: INVENTOR.

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ATTORNEY March 17, 1959 E. A. POlR lER SUCTION BOX EXTRACTION APPARATUS5 sheets sheet 4 'Filed Jan. 1 1, 1957 IN V EN TOR.

ATTORNEY March 17, 1959 E. A. POIRIER SUCTION BOX EXTRACI' ION APPARATUSFiled Jan. 11, 1957 lIIIII/IIII/IIIIIIIIIIIIIIIIIIIIIIIJJ 5 Sheets-Sheet5 INVENTOR.

53mm? aPM ATTORNEY United States Patent SUCTION BOX EXTRACTION APPARATUSErnest A. Poitier, Waterville, Maine Application January 11, 1957,Serial No. 633,601

7 Claims. (Cl. 92-51) This invention relates to methods and apparatusfor extracting water from a wet web of paper as it is passed over thewire of a paper making machine and, more specifically, the invention isconcerned with improved techniques and devices for use in conjunctionwith the suction -'boxes or other vacuum devices conventionally employedin handling a wet web of material.

In water extracting systems heretofore proposed, difiiculty has beenexperienced in dealing with variation in the amount of water occurringin the web of paper while providing for both desired papercharacteristics and a satisfactorily high rate of water removal throughdrop legs, manifold, and other water conducting elements of a suctionbox system. Such difiiculty may lead to losses in efficiency of thepaper making process as well as changes in the paper produced and, insome instances, interruption in the machine operation. A further factorto be taken into account is that the capacity of a water extractingsystem may be materially affected by turbulence produced in water drawnoil from the web as well as suspension of water in drop legs. Also theremay develop foaming and retention of air in the water which is to bereused in the paper making process.

It is a general object of the invention to deal with the problemsindicated and to improve water extracting techniques and apparatus ofthe class employing suction boxes. Another object of the invention is todevise an improved vacuum header construction for receiving extractedwater and to provide in the header apparatus a special drop legarrangement which is characterized by automatic selectivity in movingconstituent drop leg elements thereof into and out of operation. Anotherobject is to provide novel control valve means for selectivelycontrolling the operation of individual suction boxes. Still anotherobject is to improve the structural organ ization of a header and itsassociated drop leg elements, together with the seal chest into whichwater is let through the drop leg elements with a view to increasing thevelocity of flow of Water through the drop leg elements while preventingfoaming and turbulence in the seal chest.

These and other objects and novel features of the invention will be moreapparent from the detailed description of preferred embodiments of themethod and apparatus hereinafter set forth.

From long observation of the above-indicated'problems which develop inremoving water from a wet web of paper on the wire of a paper makingmachine, I have conceived of a procedure for controlling the waterextraction capacity of a suction box type syphoning system in such. away that I may disregard the requirements present in conventional vacuumextraction systems for maintaining an excess vacuum to preventequalization of vacuum and air in the system.

In this connection, I have discovered a method of extracting water whichmakes possible the application of approximately the correct amount ofvacuum at all.

times without resorting to any excess vacuum. This, I have found, may beaccomplished by automatically increasing and decreasing the extractioncapacity of the system in a carefully regulated manner varying inaccord: ance with changes in the volume of water which is drawn off bythe suction boxes from the wet sheet on the wire.

I have determined that I may modify and control the operation of thesuction boxes themselves to a degree not heretofore realized. I haveparticularly devised individual suction box valve controls. These valvecontrols, when used in a manner hereinafter described, may be regulatedto be sensitive to predetermined working vacuum conditions so that oneor more of the suction boxes may be caused to operate or to bediscontinued from operation inaccordance with changes in the flow ofwater which may be taking place from time to time in the vacuum headercasing.

In connection with controlling the water extraction capacity of mysystem in the manner conceived, I have further devised a novelstep-by-step drop leg operation employing a special vacuum header casingwhich is con: nected to a series of drop legs arranged in a single vrowat an underside of the header. With this header and drop leg arrangementI combine a specially formed header casing shape together with anoverflow partition and a series of cooperating tubular baffles locatedalong one side of the casing and vertically disposed therein above thedrop legs.

The vacuum header casing is designed so that. it presents a curved sideWall and an inclined bottom which, in conjunction with the partitionnoted, operates to guide a flow of water entering the header at an upperside thereof and conduct this water downwardly and across the headertowards its opposite side where the first tubular battle and drop leg islocated and where the partition is at its minimum height. As the flow ofwater passes along the curved side wall and over the partition anddownwardly into the first of the tubular bafiies, a vortical or swirlingmovement is induced which aids in separating air from the water in avery efficient manner.

I have also found that, by proper selection of-the height of thegraduated partition at a point immediately adjacent to the open end ofthis first drop leg, I may provide for water rising up to apredetermined level and all of this water may be conducted into thefirst drop leg. As soon as this level is exceeded, however, with thefirst drop leg being sealed and a head of water being created over same,further overflow passes across the' graduated partition at a higherpoint and then into the second drop leg. Similarly, as the level ofwater in the header progressively increases, additional drop legs willbe placed in operation, step by step. Also, with a drop' I furthercontrol turbulence at the discharge ends of the drop legs by means of aspecial seal chest member which I construct with a curved bottom sectionand individual dividing walls. directly into this curved bottom sectionand their extremities are separated by the individual walls so that theoperation of any one of the drop legs is visually. apparent at any time.A weir or bafiie is also provided, over which discharged water is causedto flow before passing to the white water reusal system. With thisarrangement of'parts, foaming and excessive'turbulence.

The drop legs are arranged to empty in the seal chest may be verydesirably reduced and controlled and much more efiicient use of thewhite water' realized.

, In the accompanying drawings, I have illustrated preferred embodimentsof a water extracting apparatus of the invention, in which- Fig. 1 is anelevational view illustrating diagrammatically a water extraction systemincluding portions of asuction box, together with conduit means, amanifold vacuum; header casing and a drop leg and seal chestarrangement;

Fig. 2 is a plan view of the apparatus shown in Fig. 1;

Fig. 3 is a plan view taken on the line 3-3 of Fig. 1;

Fig. 4 is a front elevational view of the header and drop leg unit,together with individual suction valve control mechanism of theinvention;

Fig. 5 is a cross-sectional view taken on the line 5-5 of Fig. 1;

Fig. 6 is a detail elevational view of one of the valve mechanisms forthe suction boxes;

Fig. 7 is a cross section taken on the line 7-7 of Fig. 6;

Fig. 8 is an enlarged perspective view of the vacuum header constructionof the invention;

Fig. 9 is a plan view further illustrating the structure of Fig. 8;

Fig. 10 is a detail perspective view of one of the tubular baffles;

Fig. 11 is an elevational view showing the drop leg construction of theinvention;

Fig. 12 is a detail plan view of a modified vacuum head or casingconstruction;

Fig. 13 is an elevational view of the modified construction of Fig. 12,and

Fig. 14 is an elevational view of the modified view of the samestructure.

In the apparatus of the invention, there are present a number of novelcomponents referred to above and including specifically a valvecontrolled suction box arrangement; a special vacuum headerconstruction; a manifold for connecting the suction box arrangement andvacuum header construction in cooperating working relationship; and adrop leg and seal chest assembly for conducting water away from thevacuum header member at relatively high velocity to provide a workingvacuum.

In general, it will be understood that this vacuum operates through thevacuum header and suction boxes to re move water from a web of papermoving along a wire member above the suction boxes. Under somecircumstances, an auxiliary vacuum pump P may be connected to the vacuumheader at points P1, P2 and P3. Thus,- auxiliary vacuum may be desiredin starting the machine, but for the most part is used only veryinfrequently.

Considering these several novel components in detail, attention isdirected first to Figs. 1 and 4 wherein numerals 10, 10a, ltib, 10c,16d, and 10e denote a series of conventional suction boxes over whichruns a web of paper W on a wire member.

In accordance with the invention, I provide conduits 12, 14, 16, 18, 2tand 22 which, as noted in Fig. I, extend downwardly and are connected attheir lower ends to special valve structures 11, 13, 15, 17, 19 and 21.These valves are best considered in conjunction with two othercomponents, namely, a manifold 24 and a vacuum header casing 28 which ismounted on a floor F or other desired supporting surface.

i As will be observed from an inspection of Figs. 1, 2 and 3, the valvesreferred to are connected at one side of the manifold casing 24 andprovide for automatically controlling the operation of any one or all,of the suction boxes in response to changes in flow of water through thevacuum header casing. This constitutes an important feature of theinvention and is accomplished by selectively employing the valvesindicated so that an excess vacuum is not required to be maintained and,on the contrary, a substantially constant working vacuum is provided.

To better understand the working of these valves, reference may be hadto Figs. 6 and 7 wherein is illustrated the valve structure 11consisting of an air-tight housing in which is mounted bearings 11a and111). These bearings pivotally support a valve shaft lie on which isfixed a valve element 11d. In a closed position, the valve element 11dseats against a valve seat 11c. Fixed on the shaft 110 at a pointoutside the housing is a pulley 11 which, in response to the pull of avariable weight G, acts to yieldably maintain the valve 11:! aginst theforce of a flow of water passing into the housing at the inlet 11h. Thepulley also supports at its opposite side a second weight G which can bevaried at will.

By selecting a suitable combination of weights G and G, it will beapparent that it is possible to hold the valve 11d in a substantiallyclosed position for a certain vacuum condition at the suction boxes and,yet, permit the valve to open when this vacuum condition is exceeded.Therefore, in the same way, I am enabled to set a predetermined numberof the suction boxes, through their respective valves and weights, toremain closed at vacuum conditions above a certain predetermined valuewhile a number of other boxes are similarly set to remain open withinthe noted range of working vacuum. This valve setting is hereinafter setforth in more detail with specific values being given.

The relatively stabilized flow of water thus realized from asubstantially constantly maintained vacuum range working throughindividually controlled valves as described is, in accordance with theinvention, required to be conducted to the header at relatively highvelocity. For this purpose, I have designed the manifold 24 with aparticular shape. A bottom side 24a is shaped to extend downwardly tocommunicate with an opening at the top of the header case 28. The sidesof the manifold and its top are then formed so as to taper inwardly froma width which includes all of the suction boxes to a relativelyconstricted passageway which coincides in size with the inlet opening inthe header casing and which will provide for high velocity fiow just atthe point of opening into the header casing. It is pointed out thatwater is thus drawn from a plurality of points and converged with aminimum of change of direction whereby turbulence is minimized. Themanifold may be joined to the header at this point of restriction insome suitable manner as by means of coupling members as 27.

The high velocity flow of water thus produced by the restricted end ofthe manifold and delivered to the header casing is next guided along apath to provide for stepby-step drop leg operation and to impartvertical flow to the greatest extent possible to this water as itapproaches and passes through respective drop legs.

To this end, I have constructed the vacuum header casing 28 with an endwall 28a through which is formed an inlet opening 28 at the uppersection thereof. Joined to this end wall 23a is a relatively straightsidewall portion indicated by the numeral 28c and a curved sidewallportion indicated by the numeral 281;. The two wall portions 280 and281) meet to form a relatively narrow end section 28d in the headercasing. I further provide an inclined bottom 3% which extends from apoint closely adjacent to the inlet opening 28 downwardly toward thenarrow end section 28d of the casing. This bottom,

in addition to being inclined, is shaped with a somewhat curvedconformation so that water entering the header casing through the inletopening 28' will be guided downwardly toward the relatively narrow end23:! of the casing and, at the same time, will tend to be diverted in adirection from right to left, as viewed in Fig. 2 of the drawings.

I further mount in the header casing a vertical overfio partition 32having an inclined overflow edge 32a which constitutes an importantcomponent of this header construction and which consists of a rigid wallmember arranged to extend in parallel spaced relation to the" straightsidewall portion 280 of the casing body. This overflow partition is, inaccordance with the invention, constructed of varying heights, being ata maximum height at points closely adjacent to the inlet openings 28'and at a minimum height at its point of termination in the narrow endsection 28d of the casing. In this position, it will be seen, therefore,that a flow of water passing down the inclined curved bottom 30 passesalong the partition, and at varying levels will overflow the partitionat points therealong.

The partition 32 is especially designed to cooperate with a series oftubular baflles which, as shown in Fig. 2, and in more detail in Figs. 8and 9, consists preferably of a plurality of cylindrical bodies 34, 36,38, 40, 42 and 44. These members are recessed throughout a part of theirperipheral length to provide vertical edges 34', 36', 38', 40', 42' and44' lying in spaced relation to vertical edges 34", 36", 38", 40" and42" and 44"respectively to define fluid entranceways 33, 35, 37, 39, 41,43. Each of these tubular baflies has adjacent peripheral surfacesjoined together in substantially sealed relationship. Also, each ofedges 34', 36, 38', 40, 42' and 44 throughout a part of their length isjoined as by welding or other means to adjacent surfaces of thepartition 32, as may be best seen from an inspection of Fig. 9.

It will be evident, therefore, that a flow of water will first move downto the tubular baflle 34, being confined by the partition of one sideand turned inwardly by the curved wall portion on the other side of thecasing. As a result of this combined action, the flow is directed intotheentranceway 33 of the first tubular baflie 34. The water thusentering becomes further diverted and guided around the inner peripheryof the tubular baflle from the edge 34 inwardly to take on an increasedvertical movement which is augmented with further downward travel. Anexcellent opportunity is thus produced for separation of air from theflow of water at this point.

With successively higher levels of water flowing into the header casing,overflow occurs at other points along the overflow edge 32a and astep-by-step drop leg operation then takes place. It is pointed outthat, at each succeeding level of overflow, water is constantly sealedfrom entering the remaining tubular baflies since each batfle is joinedto an adjacent one, as described above and shown in Figs. 8 ad 9.

I may, in some cases, further provide in the header casing a pluralityof transverse partitions as 45, 45', 45", etc., which are mountedbetween the curved wall 28a and the .partition 32, as shown in Figs. 2,8 and 9. The bottom edges of these partitions 45, 45, 45", etc., occurat different levels and in spaced relation to the inclined bottom 30 ofthe casing so that each partition defines an opening between itself andthe bottom of the casing through which water flows as it passes intosuccessive baflies. These transverse partitions operate to retard andcontrol the flow of water into the respective header baflles and thepartitions particularly reduce surging of water into the smaller end ofthe casing where the lowest baffle 34 occurs. It should be understoodthat the invention may be practiced without using the transversepartitions, although they may ,be employed by some purpose where itisdesired to provide a novel control of surging.

A further desirable handling of water passing from the tubular bafliesis carried out by means of a series of droplegs 50, 52, 54, 56, .58, 60and 62 which, as shown in Figs; 1 and 4, are connected at their topswith respective bottom sections of the tubular batfles above described.Preferably, these drop legs will extend through the floor F to a chambersome little distance below the floor F in order to produce anappreciable drop for the water falling through these drop legs membersand thus produce a desired working vacuum. In Fig. 1 there is indicateda second floor or basement level R which supports thereon a seal chest64 within which the extremities of the drop legs terminate so thatafluid seal is provided. Water passing out of the drop legs: is causedto flow over an overflow member 66 in the seal chest 64 and passes outthrough an outlet 68. If desired, this water may be carried back intothe system by recirculat ing mechanism 70.

In operating the drop leg and header construction described, water andair which have been extracted from the Web of paper is led away from theheaderinlet down along the inclined false bottom and across the chamberin such a manner that the tubular baflie and respective connected dropleg farthest away from the header inlet fills first. As this firstbaflie and drop leg fills, a natural vortex is established at both thetubular baffle and drop leg and air separation takes place. Thereafter,an increasing level of water may take place in the header casing. Thisincreased level of water then starts to overflow the graduated partitionat a height determined by a point immediately in front of the seconddrop leg and this second drop leg also begins to receive water in anatural vortex path of flow which does not conflict with the path offlow of water going into the first drop leg. Similarly, increasinglevels operate to place in succession the additional drop legs and, if,at any time, the level drops, the drop legs will be successively cut ofiand the flow will be taken care of by a lesser number of drop legs.Thus, it will be seen that the number of drop legs in use at any giventime is dependent upon the volume of water carried away from the web ofpaper on the wire. With low porosity, an increase in slowness in thepaper web, or a heavier weight of paper, the water carrying capacity ofthe sheet is increased. Since the table rolls of the paper makingmachine extract lesswater, a higher gallonage is delivered to the fiatsuction boxes". These conditions automatically cause additional droplegs to be brought into operation, increasing the extraction capacity ofthe system.

With an increase in porosity, freeness, or lighter sheet weights, thevolume of water delivered to the flat suction boxes is decreased. Underthis condition, fewer drop legs are utilized and the capacity of thesystem is automatically reduced.

It is pointed out that this automatic control of extraction capacityanticipates changes in slowness and freeness,l porosity, machine speeds,and other variables with the result that a constant moisture content ofthe sheet and substantially uniform porosity may be maintained at alltimes. I may, however, vary the point at which the machine operates fora desired constant moisture content of the sheet by resetting theauxiliary vacuum valve of the auxiliary vacuum pump P, shown in Fig. 1.When the new setting is established, the system will automaticallycontrol the moisture content of the sheet at this new illustratedanother important feature of the invention,

consisting of a special drop leg assembly. A casing 74 supports aplurality of drop legs as 76, 78, 80, 82, 84, 86. 9

Water is diverted along an inclined bottom 88 of casing 74 and caused tooverflow a partition 90 passing into entranceways of a series of tubularbaflles as 92, 94, 96, 98, 100. In this form of the invention, the droplegs are constructed with their lower ends of gradually increaseddiameter to form conically shaped extremities. I have found that by thusenlarging the drop legs .I may ac- First, I am able to obtain a greatervelocity at the point of water removal.

complish two desirable objectives.

Secondly, I am able to make better use of the vortical path of flowinduced by the tubular baflies and to actually 1 accentuate the vortexat each drop leg with additional opportunity being afforded to separateair from the water.

In conjunction with these tapering high velocity drop leg ends, I alsofind that the increased velocity and vortical flow overcomes anytendency for water to be suspended in nonoperating drop legs since theremay be an appreciable reduction or elimination of friction at the innerperipheral surfaces of these enlarged drop leg portions.

The seal chest 64, as illustrated in Figs. 3 and 4, consists of arectangularly shaped container which is formed along one side with acurved bottom or trough 110. Water from the drop legs collects in thistrough portion of the seal chest and overflows the partition 66 to passout through the outlet member 68. In the trough portion of this sealchest, l have provided a series of transverse partitions as 112, 114,116, 118, 120 and 122 which are, as shown in Fig. 3, so arranged as toisolate the bottom of each drop tube within the trough portion. By meansof this arrangement, when the apparatus is operating, the problem ofdetermining if any of the drop legs is not operating properly can bereadily dealt with, since a visual inspection of any one of thecompartments formed by these transverse partitions 112122 willimmediately reveal whether water is flowing out of the end of any one ofthe drop legs.

It is also pointed out that, in thus confining water which is leavingthe bottoms of the drop legs, it is confined somewhat differently thanheretofore has been the case in the art, and such water is actuallyconducted along a path which passes into a separate compartment and thenupwardly over the partition 65. This affords an opportunity forreduction in turbulence and the flow of water from the point ofdischarge at the ends of the drop legs to the overflow partition isfacilitated and foaming is minimized.

In actual operation, the extraction system of the invention has beenfound to provide various important and desirable advantages. Forexample, in one typical operation of my header with suction boxes on apaper machine wire during a four-month period, it was observed thatdrainage on the wire was increased from. a conventional rate of from 700to 900 gallons per minute to a new rate of from 980 to 1100 gallons perminute. This increase made it possible to improve sheet formation and toincrease production of paper stock upwardly as much as 20% on somegrades of paper.

It was also observed that the sheet was drier at the couch and there wasa noticeable improvement in drying rate on the driers. The automaticfeature in the header noticeably improved general machine ope ation. Itwas found that the break line at the boxes could be adjusted and set asdesired for any one grade of paper, and vacuum on the boxes wouldautomatically rise and fall, as stock or water varied, to maintain thebreak line within very close limits. Vacuum held the sheet uniform andit definitely removed more water than previous systems employed.

In running one specific grade of paper which was normally run at a speedof from 400 to 420 feet per minute and at consistencies of from 0.85 to0.90, it was possible with the method and apparatus of the invention toincrease speed to 48G5OO feet per minute at consistencies of from 0.70to 0.75 in the head box. Pressure on the driers increased with speedbut, as more water was added to the wire drier, pressure droppedappreciably as much as 10%. it was also found that the methodsubstantially eliminated the problems present in connection with waterremoval on a short wire.

It will be understood that various modifications may be made in theapparatus described. For example, in Figs. 12, 13 and 14, l have shown avacuum header casing 139 and manifold 13?. with an inlet at the top ofthe casing and a coupling member 134 mounted in the inlet so that it maybe rotated about a vertical axis in order to position the casing anddrop leg in varying positions of adjustment relative to the suctionboxes. In many plants, such an adjustable feature is extremely desirablein order to locate the drop leg extremities in a most advantageousplace. It will be understood that, with the casing rotated into adesired position, it is then secured and fastened in place by bolts orother fastenings.

Other changes of a similar nature may be made within the scope of theappended claims.

From the foregoing description, it will be evident that I have provideda method and apparatus for extracting water and improving the papermaking process in commercially significant degree and that I havematerially increased the efficiency and operation of paper makingmachines.

This application is a continuation-in-part of U. S. application SerialNo. 536,648, now abandoned, filed Septem ber 26, 1955.

Having thus described my invention, what I claim is:

1. In an apparatus for extracting water from a travelling web of paper,the combination with wire means and a plurality of suction boxes overwhich the web of paper runs in water extracting relationship, of avacuum header casing communicating with each of said suction boxes andinto which Water extracted from the suction boxes is delivered, saidvacuum header casing being provided with a plurality of drop legsleading downwardly therefrom to conduct water away from the headercasing at a relatively high velocity and produce a working vacuum, theimprovement comprising a row of ver-. tically disposed tubular bafiiesmounted within said vacuum header casing and connected to the drop legsand open at their respective side portions to provide passageways, meansextending along one side of the row of tubular bafiles to provide foroverflow of water into the said passageways of the tubular baflies stepby step at successively higher water levels in accordance with change inlevel of water delivered to the vacuum header casing from the suctionboxes.

2. A structure according to claim 1 in which the said means forproviding an overflow of water into the passageways of the tubularbaifies comprises a partition member having its upper edge varying inheight from a minimum at that end of the row of bafiles further-est awayfrom the portion of the vacuum header casing into which said waterextracted from the suction boxes is delivered to a maximum at theopposite end of the row of bafiies.

3. A structure according to claim 1 in which the vacuum header casing isconstructed with a curved sidewall portion and a substantially straightsidewall portion which meet to form a relatively narrow casing endportion, said row of tubular battles extending away from the relativelynarrow end portion in close proximity to the said straight sidewallportion of the header casing, said means for providing an overflow ofwater into the passageways of the tubular baffles consisting of anoverflow partition member which extends along one side of the row oftubular bafiles, the upper edge of said partition varying in height froma maximum at the portion of the vacuum header easing into which saidwater extracted from the suction boxes is delivered and extendingdownwardly toward the said relatively narrow end portion of the headercasing.

4. in an apparatus for extracting water from a travelling web of paper,the combination with wire means and a series of suction boxes over whichthe web of paper runs in water extracting relationship, of a vacuumheader casing communicating with each of said suction boxes and intowhich water extracted from the suction boxes is delivered, said vacuumheader casing being provided with a plurality of drop legs extendingdownwardly therefrom to conduct water away from the header casing atrelatively high velocity and produce a working vacuum, I

the improvement comprising a row of vertically disposed tubular bafiiesmounted within the vacuum header casing and having outer adjacentperipheral surfaces joined together in sealing relationship, the bottomsof the said tubular baifles being connectzd to respective drop legs,each of said tubular bafiles further having a peripheral side portionrecessed to form spaced-apart edges which define fluid entranceways, avertical overflow partition located in the vacuum header casing andextending along one side of the row of tubular baffles in contact withoutermost peripheral wall portions of each tubular baflle and in closeproximity to said entranceways, said partition having its upper edgevarying in height to provide for successive overflow of water into thesaid entranceways of the tubular baffles at progressively higher waterlevels in the header casing in accordance with changes in level of waterdelivered to the header casing from the suction boxes.

5. A structure according to claim 4 the further improvement consistingof a manifold member which is connected between the vacuum header casingand the suction boxes and which comprises an elongated conduit bodyhaving an inclined bottom which converges at sides and top portionsthereof to define a reduced conduit portion for producing a relativelyhigh velocity fluid flow at the point of entrance of fluid to the saidheader casing.

6. A structure according to claim 1 the further improvement in which thevacuum header casing is con structed with an inlet opening at the upperside thereof and said casing having a coupling member rotatable in saidinlet opening to locate the header casing in any desired position ofadjustment about a vertical axis with respect to the suction boxes.

7. That improvement in methods of controlling a vacuum exerted on atravelling web of paper at the suction boxes of a paper making machinewhich consists in causing the water extracted from the web of paper tocreate a predetermined working vacuum which is dependent upon thecharacter of the web and the volume of water being extracted at a giventime and then automatically changing the number of suction boxes inoperation in accordance with a change in flow of water to maintain thesaid working vacuum at a substantially constant value.

References Cited in the file of this patent UNITED STATES PATENTS1,926,319 Tirnmerman Sept. 12, 1933 2,200,002 Lane et a1 May 7, 19402,264,168 Poirier Nov. 25, 1941 2,264,169 Poirier Nov. 25, 19412,717,536 Clark et a1 Sept. 13, 1955

